The present invention relates to a rubber-reinforced styrene resin composition having excellent heat resistance, impact resistance and processability, as well as to a process for producing the composition.
Rubber-reinforced thermoplastic resins have excellent impact resistance, processability and surface gloss and are, therefore, used in various applications. However, when they are used as shaped articles such as interior trims of vehicles, the articles are required to have mat surface. Further, some other uses require that the said resins have heat resistance. The conventional methods of delustering shaped articles include a method in which an oxide of magnesium, calcium or the like is added. This method, however, has a drawback that the impact strength is greatly reduced and the gloss is not uniformly taken off. There is also a delustering method in which a rubbery elastomer is added. This method, however, brings about deterioration of mechanical properties (in particular, hardness and rigidity) of resin.
There is further known a delustering method in which a resin component three-dimensionally cross-linked with a crosslinking monomer is added. This method, however, is unable to give a uniformly delustered molded article and moreover reduces the processability of the resin.
Meanwhile, for the purpose of improving heat resistance, it is known to use .alpha.-methylstyrene as a comonomer or to add a maleimide copolymer. This approach, however, brings about a great reduction in processability and impact resistance.